Detecting biogenic pollution in Rybinsk Reservoir from satellite data and contact measurements

The problem of excessive algae bloom in Volga River and adjacent reservoirs has long been acknowledged. Massive algae bloom causes serious economic damage and represents a threat to water inhabitants as well as man’s life and health. From ecological point of view, cyanobacteria are the most dangerous algae type. The detection of areas most affected by algae bloom using remote sensing instruments was performed on the basis of data obtained from the following sensors: TM Landsat-5; ETM+ Landsat-7; OLI Landsat-8; Envisat MERIS and ASAR. Landsat data were used to compile color composites and select bands, the combination of which provides the best detection results. Visible satellite data were found to better manifest eutrophication zones with predomination of cyanobacteria. Envisat MERIS was used to compile suspended matter concentration charts providing rough estimates of algae content. Envisat ASAR data were compared with quasi-simultaneous visible range data. In-situ measurements of algae properties in Rybinsk Reservoir have been performed for many years by researchers of the I.D. Papanin Inland Water Biology Institute located on its coast. They regularly perform cruises to collect water samples and determine phytoplankton content. Joint analysis of Landsat-7/8 and contact data resulted in good correlation of both bloom areas of diatoms, which predominated in June 2013, and those of cyanobacteria, the lifecycle peak of which was recorded in late August – early September.